As somebody with countless packages on their way as we speak, I better remove myself from this conversation. (Looking at my orders, why I have 3 different boxes of 300 pieces of M3 nylon stand offs on order, no idea, but I suppose at least two of them are different colours)
On the USB hub, there is no diode between the DC jack and the PC USB input. That can damage a PC if you plug it in since it will backfeed 5V into the motherboard.
The resistor in the LED light is actually 39 ohms. The first 2 digits are a value the third is a multiplier. A 390 ohm would be marked 391, 39 and 1 zero.
23:40 Same goes for the smd resistors on the super cap bank. Those shunt resistors are actually 10 ohms each (5 ohms with 2 in parallel). Those are probably for current sensing.
Destroying the watch at 9:20 was not cool :-/ I feel a bit sad now. Something is wrong in this world - For such a tiny and complicated thing only 99 cent delivered - that is just crazy...
With a very small amount of research you could have taken the watch apart without destroying it. As Jan said not at all cool, almost childish from such an intelligent man.
I noticed the values for SMD resistors are being incorrectly stated on this and another video (unless I'm missing something). The resistors with "100" on them are not 100Ω. The first two digits "10" indicate the initial value. The third digit "0" indicate the decimal shift. So, 10Ω with no decimal shift is 10Ω, which can be confirmed on any number of online SMD resistor code calculators. Therefore two 10Ω resistors in parallel (10*10/10+10) is 5Ω, not 50Ω.
20:17 Wow the USB ports don't have the mechanical support clips soldered. So mechanical stress gets put on the 4 soldered pins each time you remove and install a device. Wonder how long it will last before a joint cracks? The solder looks so cruddy I almost want to say it was hand soldered but since there is solder on the unpopulated cap pads I guess it was reflow soldered. All that aside after properly soldering the USB ports not a bad USB power strip.
If you have Cap's connected in series, you increase the voltage, but capacitance goes down. It says its 120F, so if you have 6 capacirots in series, voltage will be 16.2V, but capacitance will be 120/6 = 20 Farads
The motor works by alternating the polarity of the voltage going to the coil. The rotor is a magnet with a gear on it. When the polarity changes, it re-orients. The pulses change polarity every second (because it's a clock).
Uhmm.. The current drawn by the display is absolutely tiny.. And so is the difference in resistances between the long and short wire. It has nothing to do with the voltage drop. As he said, its the accuracy that causes the measurements to differ..
Let's say the display draws 50mA. The volt drop on that extra length of cable was 100mV. That means the long cable has an extra 2 ohms of resistance. Is that likely?
they are usually running 3 LEDs in parallel, giving them 20mA each to work on. there's simply not enough voltage to drive 3 LEDs (i guess 2835 type) in series while limiting the current via resistor.
There is a load on both. How do you think the display is powered? Magic? Also longer cable will have high resistance due to length of the cable length.
16:00 Ive got loads of those little lights, basic ones, touch switch ones, dimmable ones, different LED packages etc I love them every time I see a new kind I order some one thing, isnt that resistor 39 Ohms? I thought the last digit on surface mount resistors was like the last band on through-hole resistors, a power-of-ten thing, how any 0s to add. if it was 390 Ohms it would say 391
I'm not sure but it looked like your little power bank was drawing current but it was so low that the meter couldn't count it, because there was a voltage drop when you plugged it in, if it wasn't charging then surely it wouldn't have dropped right?
Well I think the "500 mA protection" that the Chinese company indicated simply meant that one of the metal traces on the board would fuse over 500 mA and the current would stop flowing...BRILLIANT !!!! :)
I say the manufacturer should fuse that land, & make fuse accessible. The land shouldn't **burn up** as the land's orig dimensions and properties is critical for accuracy. Burn that land by mistake and jumping it will restore operation but your accuracy is probably now off a bit especially if a component's value has changed. I don't know if there's a calibration control on the pcb but if so you're lucky if you have the prior readings. -Just a suggestion-
USB LEDs: Let's have another go at that resistor, shall we. 39 x 10^0 is? And the LEDs are connected in what arrangement, bearing in mind their Vf is around 3V and the USB supply is 5V? (Repost as original deleted in error)
I have been looking at those banks of 6 supercaps for a while now, wondering if they would make a good replacement for a burglar alarm battery. I was also wondering if there would be enough energy to help start a car that has a poorly charged battery. Someone on TH-cam has done this but his supercaps were somewhat bigger than the ones in Julian's bank. I just thought these suggestions would be good ideas to include in the upcoming video dedicated to the supercap bank.
You see a voltage difference because the measuring device is at the end of different length of cable, there is a small resistance on every cable but the bigger longer the distance the bigger the resistance ant thus the smaller voltage. OhMG
Watch runs from a mainspring partially wound by that solenoid coil via a switch when the mainspring is almost out of torque. I assume the ticking is by the conventional balance wheel/escapement system. I do not know how the xtal is used. Maybe the tick is simulated audio by a chip using the crystal.
the screen and micro have enough of a load to make that small difference in the voltage on a longer cable. Thin cores and bad solder joints can do this, i have seen it many times.
John Coops I never said anything about slow learner and it is very likely that these are aluminium core cables so yes, I was talking about them. I did pay attention and I am very familiar with Chinese electronics and ohm's law so don't say I am not.
John Coops good points but they are almost certainly aluminium cored cables. If you don't believe me, look at Big Clive's videos, it is very common to see aluminium used now.
Julian your large power bank is almost the same as mine, it will not charge under certain circumstances due to sensing a very small load i forget the amount but i'm guessing that is the problem as i had it with mine,mine refuses to charge some small bluetooth headphones unless another load is put on the other usb port, hope that helps...
I think the watch might be broken. I've noticed with my power-banks that any port can be used for supply or charging. Connecting two together just equalizes the charge between the two. If I leave it plugged into my car charger, it tries to power my cars electrical system when I shut the car off.
i bought the same 19:06 with less ports and i was disappointed to discover it does not come with an external power for the socket. even the seller could not tell me what socket i could buy and use ! did you found out ?
The longer USB cable might show a lower voltage because of the voltage drop across the longer wire. There must be some kind of small current flow,since it's powering the LED meter bits.
The weird black tracks on that USB hub PCB run from the power switch towards the LED. I can't see any resistors on the video, so maybe these tracks are made out of carbon and form resistors for the LEDs?
its reading at the meter.I have tested alot of cables ,depending on length and wire size the voltage drop can be significant.If you cut the longer cable to the length of the short one and measured at that point with a VOM you would see that the gauges are reading correctly.Heck just measure the voltage at the end of the cable with a meter, you might be surprised to notice the meter on the cable usually isn't that far off.
Julian My one cell aluminum power bank, exact one that u have here charges/overcharges to 4.3V and some batteries are not happy with that fact and get extremely hot!
What if the longer cable has a lower voltage because it is longer? I had voltage problems a while ago with a longer cable that disappeared when swapped to a shorter... Hm? What if the difference in reading is caused by that...?
The closest I could find on the small SOT-23 (C73X) device is a XC61C series voltage detector from Torex Semiconductor. The other one I cannot find anything on so I presume that it is a transistor of some type like you describe. According to the data sheet I found on the voltage detector the pin out looks correct for that application.
Voltage drop only occurs when current is flowing. If the extra length of cable added say 1 ohm, the voltage drop would be V=IR i.e. number of amps x1. The displayed voltages differed even though no such current was flowing.
the extra black traces could be printed resistors. I work with washing machines and take care of the components level PCB repairs, a lot of them (particularly Bosch) have them. they're a pain. would make sense since they seem to be running to the blue LEDs.
You're probably right; when I saw them they seemed familiar, and your comment made it 'click'; they look just like the key contacts on a cheap calculator.
It may be that the longer wired unit just has more of a voltage drop, it is measuring the voltage at the end of the extension, not the beginning after all...
I think the circuitry on the back of the super caps is to prevent an uneven voltage due to capacitance variance. If one cap is smaller than the rest it will over volt. The circuitry will be to shunt over charge away and is calculated to the cap tolerance. It won't shunt much more than the cap variation.
I've had to put up the window mount air conditioning every summer for the month it's way to hot for me. This year it's still in storage. First week in July it usually goes up but it rained for the entire month with the exception of 4 days. Hasn't gotten above 27C yet. I'm in B.C. Canada.
That dual port power bank, I used to have one, one side was 1A, the other was 2A... that may also be the likely culprit behind the difference between the two ports... mine hated having both ports used at the same time so more power went to the 2A port than the 1A port.
I have some of those USB lamps. They're nice but the resistors are a little undervalued and get hot. Also, the end opposite the contacts has a solid metal strip which will probably short out your USB port is you plug it in backwards.
Actually i think the circuit on the supercapacitor-board is not for over-voltage protection but to balance the charge. When you connect capacitors in series, any variance in values causes each one to charge at a different rate and to a different voltage. The circuit shunts a resistor in series when V-in in applied and so balances the voltage over the whole pack.
The devices on that supercap board are most likely a TL431 and a NPN transistor, a MOSFET would need a gate discharge resistor and a higher voltage to run. Also you might find that the protection kicks in at 2.5V since that's the reference voltage of the TL431.
I am very interested to see you play with the supercaps. I have 6 of the maxwell 350f caps starting my car at the moment. They were the best part of £60 for a total of 50 odd farads useable capacitance. These may have some merit.
I'm guessing those are carbon film "jumper" stickers. Neat concept. Cheaper than wire jumpers I suppose. They won't carry much current, so they'd be doubling as fuses... intentionally or not.
That supercapacitor module will look like a dead short when it's empty. You might want to put a low value high wattage resistor in series initially. Too bad they aren't Maxwell brand.
Look at the value of the watch parts - how much for a 'canvas' strap? My local shop charges a pound each for those little batteries, and I am sure I would pay more than a pound for a replacement watch glass. Please send me your bin (contents that is)!
19:50 "weird tracks" is actually common technique from 80's to put additional jumpers or resistors on single side boards. It's just carbon track on epoxy resin. No cooper, no "black coating". Here it's serial resistors to LEDs.
One mistake you made, the number on smd resistor is 390, its not 390 ohms, it is 39 ohms. The first two numbers will indicate the significant digits, and the third will be the multiplier. So a 390 ohms will be actually marked with number 391 on smd resistor, and, 392 for 3.9k ohms, like so on.
Julian that 0ohm resistor is may be what is acting as a fuse since some manufactures use a 0ohm resistor as a fuse with Dell being one of them on some motherboards
Hi Julian,your 7 port USB hub,have you had any problems with yours? Mine keeps giving me USB has malfunctioned and still kind of works but not well,its usb 3.0 I think,does yours find the driver when plunged into your pc.thanks
8 ปีที่แล้ว +1
It is 10 ohm and not 100 ohm, the last digit is the number of missing tailing zeros
+Delightful Hardware That's still not 'no load' and in some circuits it's quite a lot. I was being pedantic I admit, however accuracy is relevant when doing reviews.
just orered 2 of them Smart Protection Micro USB cables. perfect for building you own usb charger and you can use these when testing. it would be interesting to see if there is any protection on this device from over voltage. as if voltage goes over 6v on vcc or any of the data pins will destroy a mobile phone. i tested this on an old iphone 4 and it indeed killed the phone lol i wonder if there is any over voltage protection then my guess it be very simple zender diode and a fast blow fuse
Oh god, I build circuit boards as a job, and some of the solder joints on that USB hub are freaking me out. I just wanna run in and reflow and touch up the whole thing. I see too much solder, large projections that are close to other joints, I see flux all over the board... Uh. Driving my OCD crazy.
usb socket leds + hub + powerbank makes for a decent work light because its self standing and the light is directed to the side and of course massive run time.
I actually bought one of these magnetic levitation things in Chicago at the Adler-Planetarium, 15 years ago. So much for new, by the way. Mine also has some LED lights that turn on and off while it spins and does look kinda cool. Thanks for the happy memories :)
The 500mA on the USB hub packaging is the maximum output of a USB 2.0 port on a standard computer. USB 3.0 has a cap of 900mA as far as I know. The power port on the side of the hub itself allows it to become a powered USB hub meaning that current can be drawn from a place other than the port it is plugged in to.
I got a a few of those "7 port" USB hubs in the past. The configuration is supposedly two 4-port hubs connected "in series", the last port of the first hub connects to the other hub, but only the three ports next to the USB lead works for data, so it's basically worse than a cheap 4-port one. The switches also just cut the 5V, leaving the data connected, which messes most devices up requiring an unplug and replug to get them going again. IMHO they shouldn't have bothered with the hub stuff, because it's not working properly like one.
Im guessing that the usb hub's 500ma protection is saying the usb bus's protection, all computers have protection for stuff taking more than 500ma on its usb port
...And that, kids, is why you don't drink and eBay!
Spot on. Got that in before i could say it.
+El Fujo that's what she said!
Could have been worse...
www.theonion.com/article/man-with-complete-mamas-family-video-library-never-1592
As somebody with countless packages on their way as we speak, I better remove myself from this conversation.
(Looking at my orders, why I have 3 different boxes of 300 pieces of M3 nylon stand offs on order, no idea, but I suppose at least two of them are different colours)
+jagardina You do realise the onion is a satirical site?
On the USB hub, there is no diode between the DC jack and the PC USB input. That can damage a PC if you plug it in since it will backfeed 5V into the motherboard.
Yeah, that is nasty!
many thanks for the this info. I was just about to do this as I got one myself.
That seems to be quite standard. Never had a PC that had an issue with it. Big Clive reviewed/destroyed one that broke macs though...
The c73x looks like a 2.7v voltage detector - could be the same as the T53 from microchip
Ebay is a addiction.
Once started buying goodies you can never stop.
Everyday looking in the mailbox is guilty pleasure......
The resistor in the LED light is actually 39 ohms. The first 2 digits are a value the third is a multiplier. A 390 ohm would be marked 391, 39 and 1 zero.
Glad I'm not the only one who spotted that.
23:40 Same goes for the smd resistors on the super cap bank. Those shunt resistors are actually 10 ohms each (5 ohms with 2 in parallel). Those are probably for current sensing.
Destroying the watch at 9:20 was not cool :-/ I feel a bit sad now. Something is wrong in this world - For such a tiny and complicated thing only 99 cent delivered - that is just crazy...
With a very small amount of research you could have taken the watch apart without destroying it. As Jan said not at all cool, almost childish from such an intelligent man.
20:13 Those are resistors. Note how those black carbon tracks connect the leds straight up to 5 volts.
I noticed the values for SMD resistors are being incorrectly stated on this and another video (unless I'm missing something). The resistors with "100" on them are not 100Ω. The first two digits "10" indicate the initial value. The third digit "0" indicate the decimal shift. So, 10Ω with no decimal shift is 10Ω, which can be confirmed on any number of online SMD resistor code calculators. Therefore two 10Ω resistors in parallel (10*10/10+10) is 5Ω, not 50Ω.
20:17 Wow the USB ports don't have the mechanical support clips soldered.
So mechanical stress gets put on the 4 soldered pins each time you remove and install a device. Wonder how long it will last before a joint cracks?
The solder looks so cruddy I almost want to say it was hand soldered but since there is solder on the unpopulated cap pads I guess it was reflow soldered.
All that aside after properly soldering the USB ports not a bad USB power strip.
If you have Cap's connected in series, you increase the voltage, but capacitance goes down. It says its 120F, so if you have 6 capacirots in series, voltage will be 16.2V, but capacitance will be 120/6 = 20 Farads
At 20:09 I'm pretty sure those are printed carbon resistors for the LEDs.
Or sun reflection flashes from solar panels erased his memory.
The motor works by alternating the polarity of the voltage going to the coil. The rotor is a magnet with a gear on it. When the polarity changes, it re-orients. The pulses change polarity every second (because it's a clock).
I think they are just square-wave pulses to drive the escapement of the mechanical part of the watch. No polarity changes needed.
OFCOURSE its going to be lower. the cable resistance is higher and you do have load on the cable to run the display and micro !!!
Under open circuit conditions it's impossible for a voltage drop to occur...
Uhmm.. The current drawn by the display is absolutely tiny.. And so is the difference in resistances between the long and short wire. It has nothing to do with the voltage drop. As he said, its the accuracy that causes the measurements to differ..
If that was the case shouldn't they account for it on the IC and calibrate it on the longer cable one?
Let's say the display draws 50mA. The volt drop on that extra length of cable was 100mV. That means the long cable has an extra 2 ohms of resistance. Is that likely?
Why dont you measure it? Maybe they ae just using really thin wire :P
Isn't that a 39ohm resistor? 3-9-0(no of zeros being 0).
Yep, you're right
And LEDs are not is series.
they are usually running 3 LEDs in parallel, giving them 20mA each to work on. there's simply not enough voltage to drive 3 LEDs (i guess 2835 type) in series while limiting the current via resistor.
I think you're wrong at 21:27. I have one of these, and it cuts out on overload. Resets itself after a few seconds when you unplug the power.
Probably not as much the accuracy of the circuit as much as the higher resistance of the longer wire.
Such a tiny current would have no effect at all. Its all due tor poor accuracy with the cheap chips. That much of wire lenght would have no effect.
Even with the really cheap and nasty USB cables you are only going to drop about 0.01V over that length with only 20mA flowing.
You also have to factor in that there IS a circuit, since the display itself draws a small fraction of power from the source too
That is what I factored in with the 20mA.
There is a load on both. How do you think the display is powered? Magic? Also longer cable will have high resistance due to length of the cable length.
16:00 Ive got loads of those little lights, basic ones, touch switch ones, dimmable ones, different LED packages etc I love them every time I see a new kind I order some
one thing, isnt that resistor 39 Ohms? I thought the last digit on surface mount resistors was like the last band on through-hole resistors, a power-of-ten thing, how any 0s to add. if it was 390 Ohms it would say 391
It is a 39ohm, you are correct 😀
39 x 10^0=39 ohm. The resistors on the super capacitor board are 10 ohms, not 100 ohms.
I'm not sure but it looked like your little power bank was drawing current but it was so low that the meter couldn't count it, because there was a voltage drop when you plugged it in, if it wasn't charging then surely it wouldn't have dropped right?
looks like things i would buy on ebay while in an intoxicated state
"I reckon I could draw A LOT more than 500mA".... sounding worryingly like photonic induction there Julian!!!
Well I think the "500 mA protection" that the Chinese company indicated simply meant that one of the metal traces on the board would fuse over 500 mA and the current would stop flowing...BRILLIANT !!!! :)
probably just took what standard usb is rated at for current draw
I say the manufacturer should fuse that land, & make fuse accessible. The land shouldn't **burn up** as the land's orig dimensions and properties is critical for accuracy. Burn that land by mistake and jumping it will restore operation but your accuracy is probably now off a bit especially if a component's value has changed. I don't know if there's a calibration control on the pcb but if so you're lucky if you have the prior readings. -Just a suggestion-
USB LEDs: Let's have another go at that resistor, shall we. 39 x 10^0 is?
And the LEDs are connected in what arrangement, bearing in mind their Vf is around 3V and the USB supply is 5V?
(Repost as original deleted in error)
Hands up! My Bad! Schoolboy errors :(
+Julian Ilett Always wondered why they went with a numeric version of the colour codes instead of just printing the value.
About volt/current meter cables; the monitor is a load... so there will be resistance... but one does seem broken.
supercapasitors; 100 is 10 ohms resistors.10, and 0 zerros efter the først ciffers: 10 ohms.
mabe the sot23 is some sort of microcontroller ?
I have been looking at those banks of 6 supercaps for a while now, wondering if they would make a good replacement for a burglar alarm battery. I was also wondering if there would be enough energy to help start a car that has a poorly charged battery. Someone on TH-cam has done this but his supercaps were somewhat bigger than the ones in Julian's bank. I just thought these suggestions would be good ideas to include in the upcoming video dedicated to the supercap bank.
You see a voltage difference because the measuring device is at the end of different length of cable, there is a small resistance on every cable but the bigger longer the distance the bigger the resistance ant thus the smaller voltage. OhMG
Maybe you should call this "search and destroy".
Watch runs from a mainspring partially wound by that solenoid coil via a switch when the mainspring is almost out of torque. I assume the ticking is by the conventional balance wheel/escapement system. I do not know how the xtal is used. Maybe the tick is simulated audio by a chip using the crystal.
A watch, assembled by someone earning a pittence then shipped half way round the world and chucked in the bin...sad really.
still got paid for it though
The ethical/economic/environmental impacts of China's activities are not the focus of this channel... At least not directly
I look at it as job security
It was crap and the assembler should be sacked.
If there is no load, then where does the 7 segment LEDs and the measuring circuit get its supply from?
What was the old mini usb leds you did buy can't find it anymore?
Where really cheap
Was from eBay I think
Could you try starting your car with the 12v super capacitor array, in place of the typical 50 pound lead acid battery...?
You lose voltage on long 5V lines... My 5m long cable drop from 5V to 4V ;(
the screen and micro have enough of a load to make that small difference in the voltage on a longer cable. Thin cores and bad solder joints can do this, i have seen it many times.
so you are saying that aluminium core cable doesnt have a voltage drop over a higher distance? wow...
John Coops I never said anything about slow learner and it is very likely that these are aluminium core cables so yes, I was talking about them. I did pay attention and I am very familiar with Chinese electronics and ohm's law so don't say I am not.
John Coops good points but they are almost certainly aluminium cored cables. If you don't believe me, look at Big Clive's videos, it is very common to see aluminium used now.
John Coops condescending.
Julian your large power bank is almost the same as mine, it will not charge under certain circumstances due to sensing a very small load i forget the amount but i'm guessing that is the problem as i had it with mine,mine refuses to charge some small bluetooth headphones unless another load is put on the other usb port, hope that helps...
the C93X on the Supercap bank seems to be XC61CC2701MR Torex voltage detector for 2.7V.. you were right about that!
Well found, many thanks for that :)
I'm confused, I thought 390 on an SMD resistor meant 39 Ohms, similarly 100 meant 10 Ohms, mmmm?
is it possible the additional pads on the USB hub were the quick blow traces acting as fuses?.
I think the watch might be broken.
I've noticed with my power-banks that any port can be used for supply or charging. Connecting two together just equalizes the charge between the two. If I leave it plugged into my car charger, it tries to power my cars electrical system when I shut the car off.
i bought the same 19:06 with less ports and i was disappointed to discover it does not come with an external power for the socket. even the seller could not tell me what socket i could buy and use !
did you found out ?
any toughts ?
I think Julian may have been trying Clive's booze recipes...
Lol. I love Clive
yesh but Clive is knowing what he's doing...
TheHirade your rude!
The longer USB cable might show a lower voltage because of the voltage drop across the longer wire. There must be some kind of small current flow,since it's powering the LED meter bits.
The weird black tracks on that USB hub PCB run from the power switch towards the LED. I can't see any resistors on the video, so maybe these tracks are made out of carbon and form resistors for the LEDs?
Hello, may I know what speaker n cam is uses to shoot this video? its very sharp and clear. Cheers. :)
its reading at the meter.I have tested alot of cables ,depending on length and wire size the voltage drop can be significant.If you cut the longer cable to the length of the short one and measured at that point with a VOM you would see that the gauges are reading correctly.Heck just measure the voltage at the end of the cable with a meter, you might be surprised to notice the meter on the cable usually isn't that far off.
Julian My one cell aluminum power bank, exact one that u have here charges/overcharges to 4.3V and some batteries are not happy with that fact and get extremely hot!
I'd pop it in the bin and get a different one, lithium batteries shouldn't get hot when charging.
What if the longer cable has a lower voltage because it is longer? I had voltage problems a while ago with a longer cable that disappeared when swapped to a shorter... Hm? What if the difference in reading is caused by that...?
Are you sure those USB lights don't have the touch function on the back where the bulb symbol is?
Just a thought.
The closest I could find on the small SOT-23 (C73X) device is a XC61C series voltage detector from Torex Semiconductor. The other one I cannot find anything on so I presume that it is a transistor of some type like you describe. According to the data sheet I found on the voltage detector the pin out looks correct for that application.
Is wire internal resistance causing voltage drop?
Voltage drop only occurs when current is flowing. If the extra length of cable added say 1 ohm, the voltage drop would be V=IR i.e. number of amps x1. The displayed voltages differed even though no such current was flowing.
there is current flowing, because meter also requires power
the extra black traces could be printed resistors. I work with washing machines and take care of the components level PCB repairs, a lot of them (particularly Bosch) have them. they're a pain. would make sense since they seem to be running to the blue LEDs.
Those strange tracks on the USB hub PCB are probably printed carbon resistors, and they are used to limit the current to the LEDs.
You're probably right; when I saw them they seemed familiar, and your comment made it 'click'; they look just like the key contacts on a cheap calculator.
I bought 35 of the USB lights six weeks ago for $7. Thanks for showing me what they will look like -- if they ever arrive!
At 24 minutes I noticed the resistors, some are (100) are aligned and some are not. Is there a reason why?
Looks like the USB hub is using printed carbon resistors for the LEDs not sure what the two at the end are though.
on the first cables you compared, the readout difference may be due to the longer cable having more resistance.
no
Hi Julian, my 7 port hub came with an adapter but went bang,not good lol.
It may be that the longer wired unit just has more of a voltage drop, it is measuring the voltage at the end of the extension, not the beginning after all...
@ 17:15 I bought one of them hubs and it stopped working after 3 days they are rubbish if you are going to us it on a computer for webcams.
the long one would drop voltage over the lengh of the cable as the display does draw some current which is not shown on the display
I think the circuitry on the back of the super caps is to prevent an uneven voltage due to capacitance variance. If one cap is smaller than the rest it will over volt. The circuitry will be to shunt over charge away and is calculated to the cap tolerance. It won't shunt much more than the cap variation.
I've had to put up the window mount air conditioning every summer for the month it's way to hot for me. This year it's still in storage. First week in July it usually goes up but it rained for the entire month with the exception of 4 days. Hasn't gotten above 27C yet. I'm in B.C. Canada.
That dual port power bank, I used to have one, one side was 1A, the other was 2A... that may also be the likely culprit behind the difference between the two ports... mine hated having both ports used at the same time so more power went to the 2A port than the 1A port.
For lightning or variable load you can buy 1.1 HUB much cheaper with white LEDs inside.
I have some of those USB lamps. They're nice but the resistors are a little undervalued and get hot. Also, the end opposite the contacts has a solid metal strip which will probably short out your USB port is you plug it in backwards.
actually there is a load , if only the measuring device, so cable length might affect it
are those on track resistors for the leds? 20:00
Actually i think the circuit on the supercapacitor-board is not for over-voltage protection but to balance the charge. When you connect capacitors in series, any variance in values causes each one to charge at a different rate and to a different voltage. The circuit shunts a resistor in series when V-in in applied and so balances the voltage over the whole pack.
The devices on that supercap board are most likely a TL431 and a NPN transistor, a MOSFET would need a gate discharge resistor and a higher voltage to run.
Also you might find that the protection kicks in at 2.5V since that's the reference voltage of the TL431.
Hi Julian, can u do a video regarding your studio setup & tips?
I am very interested to see you play with the supercaps. I have 6 of the maxwell 350f caps starting my car at the moment. They were the best part of £60 for a total of 50 odd farads useable capacitance. These may have some merit.
Those stickers on the board are jumpers. Under the ends there is no solder mask on the pcb and the black part is conductive.
I'm guessing those are carbon film "jumper" stickers. Neat concept. Cheaper than wire jumpers I suppose. They won't carry much current, so they'd be doubling as fuses... intentionally or not.
That supercapacitor module will look like a dead short when it's empty. You might want to put a low value high wattage resistor in series initially. Too bad they aren't Maxwell brand.
That's ok if the charge source is constant current
Well Elna's not too bad either, is it? (provided of course they're real, haha)
Look at the value of the watch parts - how much for a 'canvas' strap? My local shop charges a pound each for those little batteries, and I am sure I would pay more than a pound for a replacement watch glass. Please send me your bin (contents that is)!
How long affects how many volts and amps are going through an object, like a strand of 15 1M ohm resistors.
you make no sense
19:50 "weird tracks" is actually common technique from 80's to put additional jumpers or resistors on single side boards. It's just carbon track on epoxy resin. No cooper, no "black coating". Here it's serial resistors to LEDs.
Those Volt/Amp meter cables look great, I'll have to pick a few up. Cheers
One mistake you made, the number on smd resistor is 390, its not 390 ohms, it is 39 ohms. The first two numbers will indicate the significant digits, and the third will be the multiplier. So a 390 ohms will be actually marked with number 391 on smd resistor, and, 392 for 3.9k ohms, like so on.
Also those LEDs can't possibly be in series, 5 volts wouldn't be enough voltage to overcome the required voltage drop
The black track is a carbon printed resistor on the hub
Julian that 0ohm resistor is may be what is acting as a fuse since some manufactures use a 0ohm resistor as a fuse with Dell being one of them on some motherboards
Hi Julian,your 7 port USB hub,have you had any problems with yours? Mine keeps giving me USB has malfunctioned and still kind of works but not well,its usb 3.0 I think,does yours find the driver when plunged into your pc.thanks
It is 10 ohm and not 100 ohm, the last digit is the number of missing tailing zeros
capacitors in parallel with have same voltage. So only 2.7V can be pulled out of the super capacitors. Not 12V.
When you said 'no load' ... what do you think the LED display itself is?
It pretty much equals to "no load" as it's only a few mA.
+Delightful Hardware That's still not 'no load' and in some circuits it's quite a lot. I was being pedantic I admit, however accuracy is relevant when doing reviews.
Indeed it is.
just orered 2 of them Smart Protection Micro USB cables. perfect for building you own usb charger and you can use these when testing. it would be interesting to see if there is any protection on this device from over voltage. as if voltage goes over 6v on vcc or any of the data pins will destroy a mobile phone. i tested this on an old iphone 4 and it indeed killed the phone lol i wonder if there is any over voltage protection then my guess it be very simple zender diode and a fast blow fuse
What is the cameras translator software? i want it! :D
there is a .1 voltage drop in the cable due to the length, and there is a current draw front the lights on the voltmeter!
Oh god, I build circuit boards as a job, and some of the solder joints on that USB hub are freaking me out. I just wanna run in and reflow and touch up the whole thing. I see too much solder, large projections that are close to other joints, I see flux all over the board... Uh. Driving my OCD crazy.
usb socket leds + hub + powerbank makes for a decent work light because its self standing and the light is directed to the side and of course massive run time.
I actually bought one of these magnetic levitation things in Chicago at the Adler-Planetarium, 15 years ago. So much for new, by the way. Mine also has some LED lights that turn on and off while it spins and does look kinda cool. Thanks for the happy memories :)
The 500mA on the USB hub packaging is the maximum output of a USB 2.0 port on a standard computer. USB 3.0 has a cap of 900mA as far as I know. The power port on the side of the hub itself allows it to become a powered USB hub meaning that current can be drawn from a place other than the port it is plugged in to.
I got a a few of those "7 port" USB hubs in the past. The configuration is supposedly two 4-port hubs connected "in series", the last port of the first hub connects to the other hub, but only the three ports next to the USB lead works for data, so it's basically worse than a cheap 4-port one. The switches also just cut the 5V, leaving the data connected, which messes most devices up requiring an unplug and replug to get them going again. IMHO they shouldn't have bothered with the hub stuff, because it's not working properly like one.
(20:00)They skipped usb protection, because usb output port need be protection .
Im guessing that the usb hub's 500ma protection is saying the usb bus's protection, all computers have protection for stuff taking more than 500ma on its usb port
at 20:26 the black lines might be carbon printed resistors
Could it be the fast charge thing?
You had higher voltage on the short USB volt-amper-meter USB cable because of length of cable which adds resistance.
I bought one of those USB hubs and I had to resolder a bunch of bad solder joints.
Same for the resistors on the cap bank: 10 ohm each, not 100.
May I please know which tripod/mounting mechanism you are using for ur phone(?) i need a similar one for my ipod.